Buggy code:
public class SolrDispatchFilter implements Filter { final Logger log = LoggerFactory . getLogger ( SolrDispatchFilter . class ) ; protected volatile CoreContainer cores ; protected String pathPrefix = null ; protected String abortErrorMessage = null ; protected final Map < SolrConfig , SolrRequestParsers > parsers = new WeakHashMap < SolrConfig , SolrRequestParsers > ( ) ; protected final SolrRequestParsers adminRequestParser ; private static final Charset UTF8 = Charset . forName ( "UTF-8" ) ; public SolrDispatchFilter ( ) { } public void init ( FilterConfig config ) throws ServletException { } public CoreContainer getCores ( ) { } protected Initializer createInitializer ( ) { } public void destroy ( ) { } public void doFilter ( ServletRequest request , ServletResponse response , FilterChain chain ) throws IOException , ServletException { if ( ( abortErrorMessage ) != null ) { ( ( HttpServletResponse ) ( response ) ) . sendError ( 500 , abortErrorMessage ) ; return ; } if ( ( this . cores ) == null ) { <START_BUG> ( ( HttpServletResponse ) ( response ) ) . sendError ( 403 , "Server<seq2seq4repair_space>is<seq2seq4repair_space>shutting<seq2seq4repair_space>down" ) ; <END_BUG> return ; } CoreContainer cores = this . cores ; SolrCore core = null ; SolrQueryRequest solrReq = null ; if ( request instanceof HttpServletRequest ) { HttpServletRequest req = ( ( HttpServletRequest ) ( request ) ) ; HttpServletResponse resp = ( ( HttpServletResponse ) ( response ) ) ; SolrRequestHandler handler = null ; String corename = "" ; try { req . setAttribute ( "org.apache.solr.CoreContainer" , cores ) ; String path = req . getServletPath ( ) ; if ( ( req . getPathInfo ( ) ) != null ) { path += req . getPathInfo ( ) ; } if ( ( ( pathPrefix ) != null ) && ( path . startsWith ( pathPrefix ) ) ) { path = path . substring ( pathPrefix . length ( ) ) ; } String alternate = cores . getManagementPath ( ) ; if ( ( alternate != null ) && ( path . startsWith ( alternate ) ) ) { path = path . substring ( 0 , alternate . length ( ) ) ; } int idx = path . indexOf ( ':' ) ; if ( idx > 0 ) { path = path . substring ( 0 , idx ) ; } if ( path . equals ( cores . getAdminPath ( ) ) ) { handler = cores . getMultiCoreHandler ( ) ; solrReq = adminRequestParser . parse ( null , path , req ) ; handleAdminRequest ( req , response , handler , solrReq ) ; return ; } if ( path . equals ( "//admin//collections" ) ) { handler = cores . getCollectionsHandler ( ) ; solrReq = adminRequestParser . parse ( null , path , req ) ; handleAdminRequest ( req , response , handler , solrReq ) ; return ; } else { idx = path . indexOf ( "//" , 1 ) ; if ( idx > 1 ) { corename = path . substring ( 1 , idx ) ; core = cores . getCore ( corename ) ; if ( core != null ) { path = path . substring ( idx ) ; } } if ( core == null ) { if ( ! ( cores . isZooKeeperAware ( ) ) ) { core = cores . getCore ( "" ) ; } } } if ( ( core == null ) && ( cores . isZooKeeperAware ( ) ) ) { core = getCoreByCollection ( cores , corename , path ) ; if ( core != null ) { path = path . substring ( idx ) ; } else { core = cores . getCore ( "" ) ; } } if ( core != null ) { final SolrConfig config = core . getSolrConfig ( ) ; SolrRequestParsers parser = null ; parser = parsers . get ( config ) ; if ( parser == null ) { parser = new SolrRequestParsers ( config ) ; parsers . put ( config , parser ) ; } if ( ( handler == null ) && ( ( path . length ( ) ) > 1 ) ) { handler = core . getRequestHandler ( path ) ; if ( ( handler == null ) && ( parser . isHandleSelect ( ) ) ) { if ( ( "//select" . equals ( path ) ) || ( "//select//" . equals ( path ) ) ) { solrReq = parser . parse ( core , path , req ) ; String qt = solrReq . getParams ( ) . get ( QT ) ; handler = core . getRequestHandler ( qt ) ; if ( handler == null ) { throw new org . apache . solr . common . SolrException ( ErrorCode . BAD_REQUEST , ( "unknown<seq2seq4repair_space>handler:<seq2seq4repair_space>" + qt ) ) ; } if ( ( ( qt != null ) && ( qt . startsWith ( "//" ) ) ) && ( handler instanceof ContentStreamHandlerBase ) ) { throw new org . apache . solr . common . SolrException ( ErrorCode . BAD_REQUEST , ( "Invalid<seq2seq4repair_space>Request<seq2seq4repair_space>Handler<seq2seq4repair_space>('qt').<seq2seq4repair_space>Do<seq2seq4repair_space>not<seq2seq4repair_space>use<seq2seq4repair_space>//select<seq2seq4repair_space>to<seq2seq4repair_space>access:<seq2seq4repair_space>" + qt ) ) ; } } } } if ( handler != null ) { if ( solrReq == null ) { solrReq = parser . parse ( core , path , req ) ; } final Method reqMethod = Method . getMethod ( req . getMethod ( ) ) ; HttpCacheHeaderUtil . setCacheControlHeader ( config , resp , reqMethod ) ; if ( ( config . getHttpCachingConfig ( ) . isNever304 ( ) ) || ( ! ( HttpCacheHeaderUtil . doCacheHeaderValidation ( solrReq , req , reqMethod , resp ) ) ) ) { SolrQueryResponse solrRsp = new SolrQueryResponse ( ) ; SolrRequestInfo . setRequestInfo ( new SolrRequestInfo ( solrReq , solrRsp ) ) ;

Fix:
( ( HttpServletResponse ) ( response ) ) . sendError ( 503 , "Server<seq2seq4repair_space>is<seq2seq4repair_space>shutting<seq2seq4repair_space>down" ) ;